Skimmed the first report and it seems like employee-owned companies perform better up until around 75 employees, after which there's no benefit? That would explain why they aren't outcompeting the larger companies - their advantage disappears when they grow.
I’d wager that’s more to do with raising finance than organisational productivity, but I’m not aware of any actual research on something of that scale or even how to accurately study those effects without it turning into more of a qualitative theory.
Still, it’s quite an interesting possibility worth pursuing in my opinion. (Full disclosure, I work for a small nominally employee-owned company, and have mixed thoughts about how it works in practice).
